1. Field of the Invention
The present invention relates to a permanent magnet member for a voice coil motor and a voice coil motor.
2. Related Background Art
Hard disk drives (HDD) widely used as data storage means for computers have a structure in which one or a plurality of magnetic disks are arranged on the same axis and driven by a spindle motor. Data are read from and written onto the HDD by magnetic heads disposed so as to oppose the magnetic disks. The magnetic heads are driven by an actuator, a typical example of which is a voice coil motor (VCM) of a swinging type.
The VCM functions to scan the magnetic head on the magnetic disk stably at a high speed by swinging. The magnetic head has conventionally been caused to float above the magnetic disk by an airflow occurring as the magnetic disk rotates. If the magnetic disk stops rotating for some reason, however, the magnetic head may collide with the magnetic disk, thereby damaging the information stored on the magnetic disk. Therefore, the VCM is provided with a latch mechanism which is a mechanism for rapidly retracting and securing the magnetic head from above the magnetic disk. For example, Japanese Patent Application Laid-Open No. 2006-073142 discloses a structure in which a protrusion is provided at a specific position of a permanent magnet member for swinging the magnetic head by the VCM, so that the magnetic head is retracted from above the magnetic disk by magnetic attraction to this protrusion.